To improve an output performance and suppress fuel consumption in an internal combustion engine, a valve timing of an intake valve is conventionally controlled variably using a variable valve mechanism. If an internal combustion engine having this type of variable valve mechanism is operated at a valve timing for increasing an actual compression ratio, so-called pre-ignition may occur when a cooling water temperature and an intake air temperature are high.
JP2002-129994A, published by the Japan Patent Office in 2002, proposes a technique for preventing this pre-ignition by limiting a throttle opening or the like to reduce an intake air amount of an engine under operating conditions in which pre-ignition is predicted to occur.